Jens, is there any update to this issue? I purchased MK2 a while back, but had the same issue and ended up selling it to someone that used it for PAL exclusively. I would like to order the board again, but need NTSC working properly...
So far, nobody in the US has tried this. What I can do is to mod your board if you order a new one - would be great if you report back if that fixes it with the chips and PSU that you've used before. Please send me an eMail with the order ID, so I can add a note to your order. While this mod is not confirmed, I won't just ship out all boards with it.